(1) Field of the Invention
This invention relates to a metal-organic macromolecular synthetic resin composite and a process for producing the same, and more particularly to a metal-organic macromolecular synthetic resin composite having an improved adhesiveness between an organic macromolecular synthetic resin film, which will be hereinafter referred to as "organic film", and a metallic film, and a process for producing the same.
(2) Prior Art
With recent progress in electronic devices of smaller scale and higher speed, their mounted systems are calling for a higher density. For example, circuit substrates for mounting LSI are changing from conventional ceramic substrates provided with wirings of a metal such as tungsten, etc. on their surfaces by a printing technique to ceramic substrates provided with a thin-film, multilayer circuit composed of organic films of, for example, polyimide, as insulating films and metallic films of, for example, copper as conductor wirings by photolithography. That is, composites of organic films and metallic films have been regarded as important.
As to adhesion of polyimide for use as insulating films to copper for use as conductor wirings, direct vapor deposition of copper onto polyimide without any adhesive has been investigated to meet formation of finer circuit patterns and higher heat resistance. For example, Japanese Patent Application Kokai (Laid-open) No. 61-295365 discloses changing of chemical structure of polyimide in the region at a depth of about 10 to about 300 .ANG. from the surface by irradiating the polyimide surface with lower energy particles composed of reactive ions or electrons having an energy of about 50 to about 2,000 eV or photons having an energy of about 0.2 to about 500 eV, and successive vapor deposition of a metal thereon, thereby improving the adhesiveness between the polyimide and the metal.
Japanese Patent Application Kokai (Laid-open) No. 53-71182 discloses a means for corona discharge treatment of a polypropylene film surface in the atmosphere, followed by vapor deposition of aluminum thereon. Japanese Patent Application Kokai (Laid-open) No. 51-49704 discloses a means for glow discharge treatment of a plastic substrate surface, followed by electroless magnetic plating. Japanese Patent Publication No. 61-34513 discloses a means for RF plasma treatment of an organic resin film, followed by forming of a metallic film thereon by vapor deposition or plating, thereby improving an adhesiveness between the organic resin film and the metallic film. Furthermore, Japanese Patent Application Kokai (Laid-open) No. 61-95596 discloses insertion of a metal having a good adhesiveness, such as titanium, etc. between polyimide and copper, thereby improving the adhesiveness between the polyimide and the copper. Furthermore, as to polyimide, it is a recent tendency to use polyimide of low thermal expansion whose coefficient of thermal expansion approximates to those of copper and silicon in place of the so far used ordinary polyimide.
Some effects on the adhesiveness between the metallic film and the organic film are found when the organic film is placed on an electrode surface and subjected to a surface treatment by the corona discharge technique disclosed in the above-mentioned Japanese Patent Application Kokai (Laid-open) No. 53-71182 or by the glow discharge technique disclosed in the above-mentioned Japanese Patent Application Kokai (Laid-open) No. 51-49704. However, these treatments bring about a considerable inside deterioration of organic film, particularly considerable deterioration by dielectric strength, due to the strong action of electrons having a high kinetic energy. When the organic film is placed in a cyclindrical form at the position near the electrode to evade the action of electrons, no substantial adhesiveness is found between the metallic film and the organic film.
The technique disclosed in the above-mentioned Japanese Patent Application Kokai (Laid-open) No. 61-95596 is effective for the adhesiveness between the ordinary polyimide and copper to some extent, but has no substantial effect on the adhesiveness on the polyimide of low thermal expansion and copper. No disclosure is made at all therein as to other organic films than polyimide.
The present inventors made comparison of peel strength of polyimide films when PIQ (trademark of a product made by Hitachi Kasei Kogyo K.K., Japan) was used as the ordinary polyimide and PIQ-L100 (trademark of a product made by Hitachi Kasei Kogyo K.K., Japan) was used as polyimide of low thermal expansion in the technique of Japanese Patent Application Kokai (Laid-open) No. 61-95596. It was found that the peel strength was increased from 100 g/cm to 700 g/cm in the case of the ordinary polyimide, whereas it was increased only from 10 g/cm to 35 g/cm in the case of polyimide of low thermal expansion, because in the case of titanium insertion the polyimide of low thermal expansion has less functional groups capable of bonding to titanium, such as carbonyl groups, etc. Thus, in the case of polyimide of low thermal expansion, the adhesiveness was not improved and no substantial effect was obtained.
Likewise, the present inventors made comparison of peel strength in the technique of the above-mentioned Japanese Patent Application Kokai (Laid-open) No. 61-295365 between the case of ordinary polyimide and the case of polyimide of low thermal expansion. It was found that the peel strength was increased only from 100 g/cm to 300 g/cm in the former case and only from 10 g/cm to 25 g/cm in the latter case, and thus no substantial effect was obtained. One of causes seems to be that, though it is only the surface region that directly contributes to an improvement in the adhesiveness, a change is brought about to the chemical structure in a deeper region than the surface region by irradiation with particles having an energy of about 50 to 2,000 eV, resulting in deterioration of mechanical strength of polyimide itself, which leads to aggregation breakage of the entire polyimide. Furthermore, no mention is made of organic films other than the polyimide film in the above-mentioned Japanese Patent Application Kokai (Laid-open) No. 61-295365.
In the case of RF plasma treatment disclosed in the above-mentioned Japanese Patent Publication No. 61-34513, the organic film is considerably deteriorated at the inside, because of the exposure of the organic film to particles of high kinetic energy, and deterioration of mechanical strength of the organic film itself is brought about thereby.
Low energy plasma treatments are also disclosed in U.S. Pat. No. 4,393,092 and Japanese Patent Applications Kokai (Laid-open) Nos. 57-138, 60-21593 and 61-139918, and low temperature plasma treatments are also disclosed in U.S. Pat. No. 4,188,426 and Japanese Patent Application Kokai (Laid-open) Nos. 59-218789, 61-182942 and 57-186385, but no electron cyclotron resonance plasma is used in these treatments of the prior art.
RF plasma treatment is also disclosed in Japanese Patent Application Kokai (Laid-open) No. 62-116763; ionization plating in Japanese Patent Application Kokai (Laid-open) Nos. 61-183460 and 50-77863, and corona discharge treatment in Japanese Patent Application Kokai (Laid-open) No. 53-101069, but the organic films are considerably deteriorated at the inside in these treatments, resulting in deterioration of mechanical strength of the organic films themselves.
On the other hand, modification by electron cyclotron resonance plasma is disclosed in Japanese Patent Application Kokai (Laid-open) No. 62-177189, but no mention is made of the adhesiveness problem and also uses are different from that of the present invention.